#21596: Add method to formset to add a form
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Reporter: nickname123 | Owner: nobody
Type: New feature | Status: new
Component: Forms | Version: 1.6
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by nickname123):
I will elaborate. Sorry for the confusing description.
Right now, there is no easy way to add a form to a formset that I could
find documented. The formset api doesn't have anything to assist with
this internally that I could find either.
My use case is similar to the django admin where a user can click "add
another". The formset documentation suggests that this should be done
client side by javascript:
https://docs.djangoproject.com/en/dev/topics/forms/formsets/#empty-form
I think this should be possible to implement server side.
This is a simple mixin that demonstrates my intentions:
{{{
class AddableFormSet(BaseModelFormSet):
can_add_form = True
def add_form(self, **kwargs):
if self.is_valid():
# add the form
tfc = self.total_form_count()
form = self._construct_form(tfc, **kwargs)
form.is_bound = False
self.forms.append(form)
# make data mutable
self.data = self.data.copy()
# increase hidden form counts
total_count_name = '%s-%s' % (self.management_form.prefix,
TOTAL_FORM_COUNT)
self.data[total_count_name] =
self.management_form.cleaned_data[TOTAL_FORM_COUNT] + 1
@property
def add_form_key(self):
return self.add_prefix(ADD_FORM_KEY)
}}}
Now, it is easy to hook up in the view:
{{{
class CustomWizard(NamedUrlSessionWizardView):
def get_form(self, step=None, data=None, files=None):
# could be a form or formset
formish = super(CustomWizard, self).get_form(step=step,
data=data, files=files)
# support adding forms to formsets if there is post data
if data:
if isinstance(formish, BaseModelFormSet) and
formish.can_add_form:
if formset.add_form_key in data:
formset.add_form()
}}}
Now, in the template you just need something like this:
{{{
{{ formset.management_form }}
{% for form in formset %}
{{ form }}
{% endfor %}
{% if formset.can_add_form %}
<hr />
<input name="{{ formset.add_form_key }}" type="submit" value="Add
another" />
<hr />
{% endif %}
}}}
This really makes the formset more useful to me. It is simple to
implement and now doesn't require javascript to implement the "add
another" button.
It took me a pretty long time to figure out the internals to implement
this so I doubt someone new to the framework would be able to. This seems
like a logical addition to the formset api. (aside: I chose to require
is_valid() in the add_form() method because it would be frustrating for
the user to create 15 forms to find out they are all invalid. The way I
have implemented it supports multiple formsets on the same page. Which is
important for my use case that mixes individual forms and formsets in a
"form container")
It is fairly straightforward and I think that any formset used for data
entry could make use of this. So I think it would be useful to almost
anyone using a formset.
--
Ticket URL: <https://code.djangoproject.com/ticket/21596#comment:2>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
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